1. Field of the Invention
The present invention relates generally to a control system for an automotive automatic power transmission which can adapt shifting timing of the transmission to a driver's feeling. More specifically, the invention relates to an intelligent control system for an automatic power transmission which adapts a transmission shifting pattern to a vehicle driving pattern for a specific driver.
2. Description of the Background Art
In modern automatic power transmission control systems, electronic control units have been employed for precisely and optimally controlling shifting of the automatic power transmissions. Some modernized transmission control systems employ variable shift pattern strategy for adapting transmission shift patterns to individual vehicle driving patterns which are generally determined based on vehicle speed and throttle valve angular positions. For example, Japanese Patent First (unexamined) Publications (Tokkai) Showa 59-200845 and Showa 59-200848 discloses transmission control systems which employ shifting tables containing a plurality of transmission gear ratio shifting patterns.
Tokkai Showa 59-200845 discloses a transmission control system which has two transmission gear shifting pattern maps. One map is directed to a general shift pattern to be used in usual traffic. The other map is directed to a special shift pattern for extraordinarily heavy traffic. The proposed system utilizes a throttle pedal depression pattern as a parameter for selecting one of two transmission shifting pattern maps. On the other hand, Tokkai Showa 59-200848 discloses a similar transmission control system for selectively using transmission shifting pattern maps. In the proposed system, longitudinal acceleration is used as a parameter for selecting one of the maps.
In either case, the prior proposed transmission control systems employ a singular parameter for selecting shifting pattern maps. In this type of transmission control system, the selected parameter is compared with a predetermined criterion for selecting one of the preset transmission shift patterns. A drawback of this system is that the singular parameter does not always represent the actual driving condition. Therefore, a failure to detect the actual driving condition may cause erroneous selection of an inappropriate shifting pattern which will degrade the drivability of the vehicle.